Loucos Karen E, Simonin Kevin A, Barbour Margaret M
Centre for Carbon, Water and Food, Faculty of Agriculture and Environment, The University of Sydney, 380 Werombi Rd, New South Wales, 2570, Australia.
Department of Biology, San Francisco State University, San Francisco, CA, 94132, USA.
Plant Cell Environ. 2017 Feb;40(2):203-215. doi: 10.1111/pce.12865. Epub 2016 Dec 29.
Stomata represent one resistor in a series of resistances for carbon and water exchange between the leaf and the atmosphere; the remaining resistors occurring within the leaf, commonly represented as mesophyll conductance to CO , g , and leaf hydraulic conductance, k . Recent studies have proposed that g and k may be coordinated across species because of shared pathways. We assessed the correlation between g and k within cotton, under growth CO partial pressure and irradiance treatments and also with short-term variation in irradiance and humidity. g was estimated using two isotopic techniques that allowed partitioning of total g (Δ C-g ) into cell wall plus plasma membrane conductance (Δ O-g ) and chloroplast membrane conductance (g ). A weak correlation was found between Δ C-g and k only when measured under growth conditions. However, Δ O-g was related to k under both short-term environmental variation and growth conditions. Partitioning g showed that g was not affected by short-term changes in irradiance or correlated with k , but was strongly reduced at high growth CO partial pressure. Thus, simultaneous measurements of g , k and g suggest independent regulation of carbon and water transport across the chloroplast membrane with limited coordinated regulation across the cell wall and plasma membrane.
气孔是叶片与大气之间碳和水分交换的一系列阻力中的一个阻力；其余阻力存在于叶片内部，通常表示为叶肉对CO₂的导度（gₘ）和叶片水力导度（kₗ）。最近的研究表明，由于存在共同途径，gₘ和kₗ可能在不同物种间存在协同关系。我们评估了棉花在生长CO₂分压和光照处理下以及光照和湿度短期变化时gₘ和kₗ之间的相关性。使用两种同位素技术估算gₘ，这两种技术能够将总gₘ（Δ¹³C-gₘ）划分为细胞壁加质膜导度（Δ¹⁸O-gₘ）和叶绿体膜导度（gₚ）。仅在生长条件下测量时，才发现Δ¹³C-gₘ与kₗ之间存在弱相关性。然而，在短期环境变化和生长条件下，Δ¹⁸O-gₘ均与kₗ相关。对gₘ进行划分表明，gₚ不受光照短期变化的影响，也与kₗ无关，但在高生长CO₂分压下会显著降低。因此，同时测量gₘ、kₗ和gₚ表明，叶绿体膜上碳和水分运输的调节是独立的，而细胞壁和质膜之间的协同调节有限。
